Short answer: 100% safe and will provide excellent performance, subject to longer answer.
Longer answer: This is assuming your microphone is of the dynamic type, which doesn't require an external power source, unlike condenser and electret varieties with require 48V and <10V respectively. If your mic does require power, it is likely of the electret type, which the Scarlett 2i2 cannot support. Your headset specs and/or documentation may mention which type of microphone you have. The bottom line is that either your mic will work instantly (once you've turned the gain setting to the appropriate level), or not at all. In the latter case you're in murky territory as to its power requirements. At this juncture I would advise NOT attempting to apply 48V phantom power to the mic for obvious reasons, unless you're absolutely certain the mic requires that kind of power.